Design Refinement and Performance Analysis of 12Slot-8Pole Wound Field Salient Rotor Switched-Flux Machine for Hybrid Electric Vehicles

Design parameter sensitivity study and performance analysis of 12Slot-8Pole wound field salient rotor (WFSalR) switched-flux machine (SFM) for hybrid electric vehicle (HEV) applications is presented in this paper. The proposed WFSalR SFM consists of 6 armature slots, 6 field excitation coil (FEC) slots and 8 rotor poles. The main advantage of these SFMs when compared with induction machines, synchronous machines, direct current (DC) machines etc is that all the active parts such that armature coil and FEC coil are located on the stator while the rotor part consists of only single piece iron. This makes the machine more robust, simple structure and more suitable to be used for high speed HEV applications. Non-overlap armature and field windings at the stator reduces the copper consumption and also the copper losses. First of all, the initial performance, the main structure and analysis based on two-dimensional Finite Element Analysis under certain limitations and specifications are discussed. Since the initial design fail to attain the maximum torque and power, therefore the performance of machine is enhanced by refinement of several design parameters defined in rotor, FEC and armature slot area. After design refinement, WFSalR FSM has achieved the maximum torque of 22.34 Nm and power of 5.27 kW at maximum field current density, Je of 30 A/mm2 and armature current density, Ja of 30Arms/mm2 which is approximately 3 times the torque and 2 times the power of initial design.